The Alliant data site shows RL-15 as follows.
150 gr. bullet, 36.0 grains RL-15, 2450fps, at 40,600psi
170 gr. bullet, 34.1 grains RL-15, 2330fps, at 40,500psi
Obviously those are MAXIMUM loads, you should start about three grains under and work up in small increments. Those are smokin' loads for the 30/30, the 150 grain is producing 2,000 ft.lb. energy and the 170 gives 2050 ft.lb. I've found RL-15 to be about the optimum pressure/velocity rate for the 30/30 with 100% loading density and the short cylindrical granules measure very uniformly.